Telescoping linkage having detachable links with closed edges



Sept. 27, 1960 A. PFISTERER, JR 2,953,897

TELESCOPING LINKAGE HAVING DETACHABLE LINKS WITH CLOSED EDGES Filed Nov.2, 1959 INVENTOR,

A. PFisTERER, JR.

ATTYS- United States. Patent TELESCOPING LINKAGE HAVING DETACHABLE LINKSWITH CLOSED EDGES August Pfisterer, Jr., Pforzheim, Germany, assignor toAugust Pfisterer Jr., K.G., Pr'orzheim, Germany Filed Nov. 2, 1959, Ser.No. 850,450 Claims priority, application Germany Nov. 3, 1958 4 Claims.(Cl. 59-79) The present invention relates to expansi ble link straps,

and more specifically to an expansible link strap for wrist watches andthe like, which comprises a series of links the longitudinal axes ofwhich extend in the transverse direction of the strap, each of saidlinks being comprised of a pair of box-like link elements including anouter decorative link element and a similar intermediate link elementslidable within said outer decorative link element. Expansible linkstraps of this type have already become known which comprise decorativelink elements with open adjacent sides from which laterally openintermediate link elements can be partially withdrawn, said intermediatelink elements having a longitudinally slotted bottom engaged by a lugprovided in one'of the open sides of the decorative link elements. The,lug compresses a spring, located inside the intermediate link ele mentbetween between the lug in the decorative link element and onetransverse wall of the intermediate link element, when the strap isexpanded, and urges the intermediate link element back into thedecorative link element when the tension on the strap is relaxed, thuscausing the expanded strap to contract.

It is a drawback of such straps that it is possible to see through theopen ends of the intermediate link elements when the strap is expanded.Apart from imparting to the strap a general appearance of hollowness andfragility, this form of construction actually facilitates buckling anddeformation because of the absence of end walls. It would be quitepossible to form end walls on such intermediate link elements, but thiswould gravely interfere with the work of assembling the link elements,since the springs must be in position before the intermediate linkelements can be connected. In practice this would be diflicult toeflfect and increase the cost of production.

It is the object of the present invention to overcome this drawback andat the same time ofier a satisfactory solution of the problem ofsimplifying the work of assembly.

An important feature of the invention consists in that part of thematerial to be stamped out of the bottom wall of the intermediate linkelement for forming the longitudinal slots is left connected with thebottom walland is bent inwardly near the strap edges to form guide wallsadapted to locate the compression spring between them, an opening beingprovided in one transverse wall of each intermediate link element forthe introduction therethrough of the spring, and a cross plate servingto close said opening and retain the spring when the strap is expanded.In this form of construction it is impossible to see through theintermediate link elements, and the guide walls prevent the intermediatelink elements from buckling when they are squeezed. Moreover, after thesprings have been inserted into the intermediate link elements unskilledlabour can be employed to connect the link elements together withoutusing tools, and the production ice of the completely closedintermediate link elements. is

therefore cheap.

A preferred embodiment described by way of example and accompanyingdrawing in which:

Fig. 1 is a top plan view, partly in section, of a por tion of anexpansible link strap according to the inven .tion, some strap linksbeing shown in expanded and some in contracted position;

Fig. 2 is a side view of a portion of the strap, likewise showing somelinks in expanded and some in contracted position;

Fig. 3 is a perspective view of a link in expanded position, said linkbeing comprised of a pair of box-like link elements including an outerdecorative link element and a similarly intermediate link element; V

Fig. 4 is a similar view of an inverted intermediate link element, and Ip l Fig. 5 is a similar view of a cross plate. 7

As shown in Fig. 1, an expansible link strap according to the inventioncomprises a series of links the longitudinal axes of which extend in thetransverse directionof the strap, each of said links being comprised ofa pair of boxlike link elements including an outer decorative linkelement A and a similar intermediate link element B slidable within saidouter decorative link element. 7

Each of the decorative link elements A has a topwal-l 2', a bottom wall2, end walls 9 and open transverse sides 1 and 1". At the transverseside 1 the bottom wall 2 of the link element A is formed with two spacedlugs 3 which are bent perpendicularly upright. The intermediate linkelements B are inserted into the decorative link elements A from theside 1' which is opposite the side 1 formed with said lugs 3. Each ofthe intermediate link elements B has a top wall 4', a botto-m wall 4, arounded transverse wall 11, a straight transverse wall 12 andlongitudinal slots 5 formed in the bottom wall 4 and spaced the samedistance apart as said lugs 3 so that the slots 5 are engageable by thelugs 3. A compression spring 6 contained inside the intermediate linkelement B is held by said lugs 3 and is therefore compressed if theintermediate link element B is partially withdrawn from the link elementA. The portion of the intermediate link element B which projects fromthe side 1 of link element A isfastened to the adjacent decorative linkelement A by means of a snap-action link pin 7 whichis pushed crosswisethrough the intermediate link element B, and which has inwardly yieldingpin ends 7 insertable into holes 8 in the end walls 9 of the adjacentdecorative link element A. i

The longitudinal slots 5 in the of the invention will new be withreference to the bottom wall 4 of the intermediate link element B forengaging the'lug s 3 of the inwardly into the inside of the intermediatelinklele rnent B so as to form guide walls 10 for the compressiolnspring 6. The guide walls 10 are shorter than the length of the slots 5and do not extend into the rounded transverse wall 11, nor do theyextend tothe strai ght transverse wall 12 of the intermediate linkelement B. fl-Iowever, the slots do extend about half way into therounded transverse wall 11. Lateral lugs 13 are formed on the straighttransverse wall 12 and are bent over the edge of the bottom wall 4 ofthe intermediate link element which at these places is provided withcooperating depressed edge portions 14 so that the lugs 13 lie flushwith the general surface of the bottom wall 4 (Fig. 4). The straighttransversewall 12 has an opening 15 with ends 15 and of a widthcorresponding with the distance between the two guide walls 10. Thecompression spring 6 can thus be inserted into the intermediate linkelement B through said opening 15 and will then be guided by the twoguide walls 10. After insertion of the compression spring 6, the opening15 is closed in that a cross plate 16 (Fig. is slidably placed acrosssaid opening 15. As shown in Fig. 4, the guide walls 10 have out ends10' and 10" and said cross plate 16 is inserted between the cut ends 10'of the guide walls 10 and the straight transverse wall 12 of theintermediate link element B. The cross plate 16 has a central olfsetportion 17 between shoulders 17'. The central offset portion 17 has alength equal to that of the opening 15 in the straight transverse wall12 and engages said opening 15, the shoulders 17' bearing against theends 15 of the opening 15 and there- -by preventing the cross plate 16from shifting after it has been correctly inserted. The particularconformation of the cross plate 16 does not therefore reduce theavailable withdrawal of the intermediate link element B from the linkelement A by introducing an additional thickness of the material, andthe compression spring 6 is at the same time located by a recess formedby the oliset portion 17 of the cross plate 16.

The intermediate link element B can then be readily inserted into thedecorative link element A from the open transverse side 1 thereof andpushed through the same, as shown in Fig. 3. In this position the linkpin 7 can be pushed through the intermediate link element B and betweenthe rounded transverse wall 11 and the cut ends 10" of the guide walls10, and connected with the adjacent decorative link element A.

The invention may be embodied in other specific forms without departingfrom the spirit or essential character.

istics thereof. The present embodiment is therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforegoing description and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

I claim:

1. An expansible link strap for Wrist watches and the like comprising aseries of links the longitudinal axes of which extend in the transversedirection of the strap, each of said links being comprised of a pair ofbox-like link elements including an outer decorative link element with atop wall, a bottom wall, end walls and open transverse sides and asimilar intermediate link element slidable within said outer decorativelink element and having a top wall, a bottom wall, a rounded transversewall and a straight transverse wall, two spaced lugs formed on thebottom wall at one of the open transverse sides of the outer decorativelink element and projecting perpendicularly upright from said bottomwall, two spaced slots extending with parallel longitudinal outer andinner edges in the bottom wall of the intermediate link element in thelongitudinal direction thereof and engaged by said lugs,

.guide walls formed integral with the bottom wall of the intermediatelink element and projecting perpendicularly from the outer longitudinaledges of the slots into the intermediate link element, an openingprovided in the straight transverse wall of the intermediate linkelement, a removable cross plate for closing said opening, and acompression spring in said intermediate link element, guided by saidguide walls and adapted to be compressed by the lugs upon expansion ofthe strap.

2. An expansible link strap for wrist watches and the like comprising aseries of links the longitudinal axes of which extend in the transversedirection of the strap, each of said links being comprised of a pair ofbox-like link elements including an outer decorative link element with atop wall, a bottom wall, end walls and open transverse sides and asimilar intermediate link element slidable within said outer decorativelink element and having a top wall, a bottom wall, a rounded transversewall and a straight transverse Wall, two spaced lugs formed on thebottom wall at one of the open transverse sides of the outer decorativelink element and projecting perpendicularly upright from said bottomwall, two spaced slots extending with parallel longitudinal outer andinneredges in the bottom wall and half way into the rounded transversewall of the intermediate link element in the longitudinal directionthereof and engaged by said lugs, guide walls formed integral with thebottom wall of the intermediate link element and projectingperpendicularly from part of the outer longitudinal edges of the slotsinto the intermediate link element, an opening provided in the straighttransverse wall of the intermediate link element, a removable crossplate for closing said opening, and a compression spring in saidintermediate link element, guided by said guide walls and adapted to becompressed by the lugs upon expansion of the strap.

3. An expansible link strap for wrist watches and the like comprising aseries of links the longitudinal axes of which extend in the transversedirection of the strap, each of said links being comprised of a pair ofbox-like link elements including an outer decorative link element with atop wall, a bottom wall, end walls and open transverse sides and asimilar intermediate link element slidable within said outer decorativelink element and having a top wall, a bottom wall, a rounded transversewall and a straight transverse wall, two spaced lugs formed on thebottom wall at one of the open transverse sides of the outer decorativelink element and projecting perpendicularly upright from said bottomwall, two spaced slots extending with parallel longitudinal outer andinner edges in the bottom wall and half way into the rounded transversewall of the intermediate link element in the longitudinal directionthereof and engaged by said lugs, guide walls formed integral with thebottom wall of the intermediate link element and projectingperpendicularly from part of the outer longitudinal edges of the slotsinto the intermediate link element, an opening provided in the straighttransverse wall of the intermediate link element, a removable crossplate for closing said opening and disposed between the straighttransverse wall with its opening and the relative ends of the guidewalls, said cross plate being formed with a central oifset portiondefined by shoulders which fit into said opening, and a compressionspring in said intermediate link element, guided by said guide walls andadapted to be compressed by the lugs upon expansion of the strap.

4. An expansible link strap as claimed in claim 2, wherein a snap-actionlink pin is inserted between the rounded transverse wall of theintermediate link element and the relative ends of the guide walls andthe yielding pin ends are insertable into corresponding holes in theadjacent decorative link element for articulating the intermediate linkelement with said decorative link element.

No references cited.

